1. Field of the Invention
The invention relates to a scroll saw, more particularly to a saw-blade driving device for a scroll saw.
2. Description of the Related Art Referring to
FIGS. 1 and 2, a conventional scroll saw is shown to include an elongated machine base 10, a table 11, a C-shaped blade-holding arm 12, a generally vertical saw blade 15, and a saw-blade driving device.
As illustrated, the table 11 is mounted pivotally on the machine base 10, and is adapted for placement of a workpiece to be sawn such that the table 11 is rotatable about a horizontal axis that extends in a longitudinal direction of the machine base 10.
The blade-holding arm 12 is fixed on the machine base 10, and has upper and lower arm portions 121, 122 that extend in the longitudinal direction of the machine base 10. The saw blade 15 is held between front ends of the upper and lower arm portions 121, 122 of the blade-holding arm 12 via two chucks 14, and extends perpendicularly through the table 11. The saw-blade driving device includes a motor 16, and a linkage consisting of an upper swing arm 13, a lower swing arm 13xe2x80x3, a generally vertical driving rod 18, a counterweight plate 17, and a crankpin 162. The motor 16 is disposed in the machine base 10 below the table 11, and has a motor shaft 160 which extends in a transverse direction of the machine base 10. The motor shaft 160 is shaped as a crankshaft, and is provided with the crankpin 162. The counterweight plate 17 is sleeved fixedly on the motor shaft 160. The upper and lower swing arms 13, 13xe2x80x3 extend in the longitudinal direction of the machine base 10, and have middle portions that are disposed pivotally and respectively on the upper and lower arm portions 121, 122 of the blade-holding arm 12 so that the upper and lower swing arms 13, 13xe2x80x3 respectively rotate about two horizontal axes which extend in the transverse Direction of the machine base 10, front ends provided with the chucks 14 for holding upper and lower ends of the saw blade 15, and two rear ends connected pivotally to each other by means of a vertical link (not visible) for synchronous movement. The driving rod 18 has an upper end connected pivotally to the lower swing arm 13xe2x80x3 adjacent to the front end thereof, and a lower end connected pivotally to the crankpin 162. Under this condition, rotation of the motor shaft 160 results in reciprocal and vertical movement of the driving rod 18 relative to the machine base 10 and consequently reciprocates the saw blade 15 on the blade-holding arm 12.
One disadvantage that results from the use of the aforesaid conventional scroll saw resides in that in order to form bevel surfaces on the workpiece (not shown) during the sawing operation, the table 11 is tilted. Collision between the table 11 and the motor 16 is thus possible since the motor 16 extends from the machine base 10 in the transverse direction, thereby adversely affecting the sawing operation.
Therefore, the object of this invention is to provide a scroll saw which is clear of the aforementioned drawback that results from the use of the conventional scroll saw.
Accordingly, the scroll saw of the present invention includes an elongated machine base, a table, a C-shaped blade-holding arm, a generally vertical saw blade, and a saw-blade driving device. The table is mounted pivotally on the machine base, and is adapted for placement of a workpiece to be sawn, and is rotatable about a horizontal axis that extends in a longitudinal direction of the machine base. The C-shaped blade-holding arm is fixed on the machine base, and has upper and lower arm portions that extend in the longitudinal direction of the machine base and that have front ends. The saw blade is held between the front ends of the upper and lower arm portions of the blade-holding arm, and extends perpendicularly through the table. The saw-blade driving device includes a motor and a linkage. The motor is disposed within the machine base, and is provided with a motor shaft that extends in the longitudinal direction of the machine base. The linkage interconnects the motor shaft and the saw blade so as to reciprocate the saw blade relative to the blade-holding arm.